Read from the FDA’s warning-letter index

FDA warning letters on peptides and GLP-1 drugs

The FDA has sent 164 warning letters that mention a peptide or GLP-1 drug Peptlas tracks. 77 of them are from the last 12 months.

Most mention semaglutide (149) or tirzepatide (113). 29 mention at least one of the other compounds we track, led by retatrutide (21). The newest, dated Sep 24, 2026, went to Cheap Medicine Shop/www.cheapmedicineshop.com.

Searched Oct 15, 2026 (ET) · 164 letters · 18 of 26 compounds mentioned

What a warning letter is

When the FDA finds what it believes are significant violations of federal law, it often tells the company in a warning letter. The letter lists the problems and gives the company a deadline to respond with corrections, and the company can explain why it disagrees. If the violations continue, the FDA may take enforcement action without further notice.

A letter does not change a compound’s legal status. And a letter that mentions a compound is not always about selling it, so read the letter before you cite it.

By compound

  • Semaglutide (compounded)Restricted149 letters · latest Sep 24, 2026: Cheap Medicine Shop/www.cheapmedicineshop.com
  • Tirzepatide (compounded)Restricted113 letters · latest Sep 18, 2026: Empower Clinic Services, LLC dba Empower Pharmacy
  • RetatrutideRestricted21 letters · latest Aug 24, 2026: NuScience Peptides LLC
  • CagrilintideRestricted5 letters · latest Mar 31, 2026: PekCura Labs
  • PT-141 (bremelanotide)Restricted5 letters · latest Aug 24, 2026: NuScience Peptides LLC
  • SS-31 (elamipretide)Restricted5 letters · latest Aug 24, 2026: Peak Performance Peptides
  • TesamorelinRestricted5 letters · latest Aug 24, 2026: NuScience Peptides LLC
  • NAD+In limbo3 letters · latest Apr 7, 2026: ProRx LLC
  • BPC-157In limbo2 letters · latest Jun 12, 2023: Warrior Labz SARMS
  • IpamorelinIn limbo2 letters · latest Aug 24, 2026: NuScience Peptides LLC
  • LL-37 (cathelicidin)In limbo2 letters · latest Nov 10, 2021: Advanced Nutriceuticals, LLC dba The Guyer Institute of Molecular Medicine
  • SermorelinCompounding-legal2 letters · latest Dec 10, 2024: Xcel Research LLC
  • TB-500 (Thymosin Beta-4)In limbo2 letters · latest Jan 20, 2026: GenoGenix LLC
  • AOD-9604In limbo1 letter · latest Jan 26, 2022: Innoveix Pharmaceuticals Inc
  • EpitalonIn limbo1 letter · latest Jan 20, 2026: GenoGenix LLC
  • Melanotan IIIn limbo1 letter · latest Feb 15, 2024: LightEyez Limited
  • SelankIn limbo1 letter · latest Nov 10, 2021: Advanced Nutriceuticals, LLC dba The Guyer Institute of Molecular Medicine
  • SemaxIn limbo1 letter · latest Nov 10, 2021: Advanced Nutriceuticals, LLC dba The Guyer Institute of Molecular Medicine
  • CJC-1295In limboNo letter mentions it
  • DihexaIn limboNo letter mentions it
  • Emideltide (DSIP)In limboNo letter mentions it
  • GHK-CuIn limboNo letter mentions it
  • Kisspeptin-10RestrictedNo letter mentions it
  • KPVIn limboNo letter mentions it
  • MOTS-cIn limboNo letter mentions it
  • Thymosin Alpha-1In limboNo letter mentions it

The last 12 months 77 letters, newest first

Earlier letters 87 letters, since Feb 2, 2021

Show all 87

Asked and answered

Has the FDA sent warning letters about BPC-157?
Yes. 2 FDA warning letters mention BPC-157, the latest to Warrior Labz SARMS on Jun 12, 2023. Its U.S. status on Peptlas: In limbo (PCAC recommended listing (8-6, Jul 23, 2026) - advisory only; still not on the 503A list).
Has the FDA sent warning letters about retatrutide?
Yes. 21 FDA warning letters mention retatrutide, the latest to NuScience Peptides LLC on Aug 24, 2026. Its U.S. status on Peptlas: Restricted (Investigational only - no approved form exists anywhere; cannot be compounded; FDA warning letters target sellers).
Does a warning letter change whether a peptide is legal?
No. It tells one company that the FDA believes it broke federal law and gives it a deadline to respond with corrections. Each compound’s legal status is on its own page, with the rule or decision it rests on.
How does Peptlas find these letters?
We search the FDA’s warning-letter index for every compound we track and its other names, and count a letter only when its text contains the name. A watcher repeats the search every six hours, and a person reviews each new letter before this page changes.

Sources

Dates are the letter dates, not the dates the FDA posted them. A watcher searches the index every six hours; when a new letter mentions a compound we track, a person reviews it before this page changes.